generally consists in obliging those persons whom there is probable ground to suspect of.future misbehavior..to give full assurance to the public that .guch offense as ia apprehended shall not happen, by finding pledges or securities to keep the peace, or for their good behavior. ::Sec 4-.Bl. Comm. 251; 4 Steph. Comm. 200.'5 °°. ° .: 1